Palletizing machines of this type for automatically or semi-automatically palletizing elongated products are well known, for example, machines to palletize cylindrical tubes directly and continuously as they exit the production line. Palletizing tubes is a delicate operation because when they are arranged side by side and in superimposed layers, they have a tendency to roll on top of each other. This problem can be resolved by interlacing the rows of tubes using a tie which may be a string, a ribbon, a strap, a band, a fabric strip, a film or other equivalent means made of fiber, wire, natural and/or synthetic material, said tie being woven, non-woven, extruded, or manufactured by any other method, and the function of said tie being to maintain the rows in place and prevent the tubes from falling before the pallet is encircled. This interlacing is usually done manually by an operator who must place the spool or spools of tie material on either side of the pallet as the rows advance. Since the tubes may reach up to ten feet in length, if they are very long the number of spools of interlacing required will double, necessitating more than one operator.
Publication No. WO 02/06121 by the same applicant describes a palletizing machine equipped with an interlacing device for automatically interlacing tubes while they are being palletized. This interlacing device comprises two supports located on either side of the transport pallet and designed to alternately receive one or more spools of interlacing material. This device also comprises a gripping means located on the device which grips the tubes or located on an additional gripping device, designed to displace the spool or spools of interlacing material from one support to the other while the rows of tubes placed upon the transport pallet are advancing. Since this interlacing device is integral with the palletizing machine, it does not offer an optimal industrial solution. Actually, if the gripping means are located on the tube gripping device, it is necessary to interrupt the palletizing cycle to move the spool of interlacing material from one support to the other, which has a negative impact on the global output of the palletizing machine. If the gripping means are located on a gripping device that is supplemental to the tube gripping device, manufacturing the interlacing device becomes complex and has a negative impact on the global cost of the palletizing machine.
U.S. Pat. No. 5,769,601 proposes an interlacing device that is integrated with a palletizing machine and operating in the reverse manner of the machine that is the object of the invention. The tubes are moved to the upper portion of the machine by a conveyor and pushed onto a pallet by cylinders, forming a row. After each row, the pallet descends one level to permit formation of a new row. A winder moving in perpendicular translation to said tubes unfurls a strip of paper or plastic film between the rows of tubes to maintain them in place. This interlacing device is not transferable to the palletizing machine of the invention and does not permit interlacing of long tubes.